A premium boss killer, Scathach is often one of the first names to be considered when taking on tough challenge quests thanks to her amazing burst on her Noble Phantasm, guaranteed stun, an on-demand dodge and great coverage with God Slayer. Given proper support, she can also be a strong critical damage dealer. Thanks to her overloaded kits and early access to a Noble Phantasm Interlude, Scathach is an amazing addition to any player's roster, and remain relevant for a long time even after more Servants are added.

While somewhat similar, Scathach is tougher to utilize properly than servants like Okita mainly because of how she generates NP and stars. Spotting a seemingly worse NP generation and star generation, two 2-hits Quick cards, and only one 3-hits Art card, most would assume she would have trouble filling her NP bar. However, two 6 hits Buster and a 7 hits Extra card make her deceptively good at generating NP and critical stars. Furthermore, due to her 1st skill, more often than not Scathach will absorb critical stars to further improve her NP Generation with crit Art card.

Due to her hits count, outside of relying on teammates or Craft Essences' support, Scathach can effectively fill her NP bar by either doing an ABB Brave chain or putting her Art cards with some critical stars at the end of any non-Brave chain (preferably with another teammate Art card in the 1st slot) and hope that she does critical damage. Similarly, Scathach can generate a good amount of critical stars by doing a QBB Brave chain.

Consequently, because of her unique circumstance, Scathach's effectiveness in both NP gen or star gen will drop significantly if she cannot get the desired Brave chain or critical stars support. This combined with the unreliable rate to trigger her star absorption and crit damage buffs are her main downsides.

Strengths

Extremely high burst on her Noble Phantasm due to early Interlude access, Primordial Rune, potential God Slayer boost and good attack stats

Effective in hard boss fights due to having a guaranteed stun on her Noble Phantasm, an on-demand dodge, and God Slayer covering a lot of the enemies' roster

Can function well as a crit damage dealer thanks to decent star generation, high hits count Buster cards and Extra card as well as a critical star absorption and critical damage self-buffs

Can buff other Quick-oriented servants with Primordial Rune

Weaknesses

Her first skill has 80% to trigger the two other buffs separately, making it unreliable

Reliant on getting the correct Brave chain or critical hits to generate NP or critical stars

Kaleidoscope / Imaginary Element / Halloween Princess: Starting NP bar is never bad on Scathach, particularly in fights where she needs quick access to her NP such as Archer 40 AP Daily Quest

Victor of the Moon: Scathach can deal a lot of damage with Victor of the Moon when her 1st skill triggers

After-Party Order!: Boosts her two main damage tool - Buster cards and her Noble Phantasm by a good margin while only requiring 9 party cost. If this CE is not limit broken, it can be substituted with CEs like Imaginary Around or Limited / Zero Over

Seal Designation Enforcer: Remove Scathach's reliance on her 1st skill to hog critical stars, which is quite beneficial on her as it improves both her damage output and NP generation

Fragments of 2030: Extremely potent when there are multiple copies being held by teammates. Either her teammates or Scathach herself can make use of the critical stars generated by this CE.

There is no bad skill in Scathach's kit. All of the bonus she gains are useful and potent enough to warrant maxing all three of her skills as soon as possible.

Of them, Primordial Rune is the best skill in general, due to its massive influence on her Noble Phantasm's performance and targetable nature, which makes her a lot more flexible when paired with other Quick-oriented Servants like Okita.

God Slayer has immensely useful coverage as plenty of bosses in the game are servants with Divinity, or are Undead. The bonus damage from God Slayer makes Scathach the hardest counter to bosses like Gilgamesh, as she often just one shots him with a Brave chain or her NP with God Slayer active.

Wisdom of the Abyss provides an on-demand dodge, which is extremely important in harder boss fights. Unfortunately, the unreliable nature of her other buffs that are layered with this skill (star absorption and critical damage up) make it less appealing. Nonetheless, this skill is still worthwhile to max just to get the reduced cooldown on the dodge.

Zhuge Liang (Lord El Melloi II): Waver allows Scathach to reach her performance high much more consistently. He not only fixes Scathach’s NP gain problems (so she can unleash the rocket stick), but also gives her a consistent crit damage buff.

Cursed Arm Hassan: Hassan has almost everything else Scathach could need, namely critical stars. His quick-focused deck allows him to create Quick chains on down turns for guaranteed stars, and his low star weight allows Scathach to crit more consistently.

Gaius Julius Caesar: I recommend him a lot, but he is very good quick oriented support who can complete Scathach’s damage buff trinity and provide her with even higher critical damage buffs.